As is well known, the operation of gasoline engines results in the release into the atmosphere of undesirable quantities of nitrogen oxides (generally referred to as NO.sub.x). In order to ameliorate this adverse situation, considerable effort has been devoted to the development of catalyst systems to control the amount of NO.sub.x emitted by gasoline engines, and especially by motor vehicles powered by gasoline engines. The most recent developments in the field involve the development of so-called three-way catalysts--i.e., catalysts which are designed to control the emission of NO.sub.x, carbon monoxide, and unburned hydrocarbons. While such catalysts can be pelletized catalysts, the type of exhaust gas catalysts currently preferred in the art are the monolithic catalysts. For further details concerning such developments, reference may be had, for example, to Kirk-Othmer, Encyclopedia of Chemical Technology, John Wiley & Sons, Volume 5, copyright 1979, pages 48-50, and references cited therein (listed on page 56 thereof).